The smear effect induced by plastic drainage board installation significantly impacts soft ground improvement,yet the influence of pile boot type on the smear zone remains unclear.In this study,transparent soil and particle image velocimetry (PIV) techniques are used to establish a “sand-over-clay” layered foundation model.Visualization tests are conducted with five pile boot types (circular/irregular/triangular cross-section stick,plate-type,and duckbill-less circular) under varying insertion depths.The research show that：1） The smear zone comprises a strong smear zone and a weak smear zone.Within the strong smear zone (0d-4d,d represents diametre of the sleeve),the lateral soil displacement attenuation rate reaches 75%/d.In contrast,the weak smear zone exhibits an attenuation rate of ＜5%/d.2) For dredged slurry and coastal silt,the strong smear zone consistently extends to 4d regardless of pile boot type.However,the weak smear zone ranges from 7d to 10d depending on boot geometry,with irregular stick boots reaching 10d and circular boots limited to 7d.3) When insertion depth increases from 10d to 14d,the weak smear zone expands from 6d to 9.5d,while the relative displacement u/d (u represents soil horizontal displacement) within the strong smear zone increase 0.04.The research provides quantitative criteria for selecting pile boots and assessing smear effects in engineering practice.